The demand for aluminum wheels increases each year as automotive manufacturers move away from wheels that are fabricated from steel. The reason for the automotive industry's shift from steel wheels to aluminum wheels is driven by a variety of factors. For example, aluminum wheels are lighter than their steel counterparts and therefore contribute to the overall weight savings of an automotive vehicle. The decrease in overall weight increases the fuel economy and improves the performance and handling of the automotive vehicle. Additionally, many consumers feel that aluminum wheels offer superior aesthetic qualities over their steel counterparts.
The aesthetic characteristics of aluminum wheels are improved by surface treatment processes to the metal, such as fine machining and/or polishing or buffing. Once the metal is imparted with the desired finish and luster, it is then preserved by application of an protective coating. Technologies typically utilized for this protection consist of clear lacquers either in liquid or powder form followed by a thermal curing step in order to achieve full polymerization. In some instances, intermediate color coats are applied so that to further enhance the styling of the finished product.
In other instances, aluminum wheels are coated or decorated with an image or pattern to enhance the wheel's aesthetic qualities. The techniques used to coat or decorate the vehicle wheel are well known in the art. For instance, dye sublimation, ink jet printing, screen printing, pad printing, or specialized liquid/powder spraying may all be used to coat the vehicle wheel with the desired image. Typically, the metal substrate of a vehicle wheel is at peak strength (i.e. T6 temper) prior to being coated with the desired image. In order to reach peak strength, the vehicle wheel is usually subjected to a number of annealing steps after initial fabrication, such as solution heat treatment and aging. In combination with surface protection and decoration processes, these steps require time and power which ultimately leads to increased production and consumer costs. Therefore, there exists a need for a method to reduce the total number of annealing steps needed to fabricate a coated/decorated vehicle wheel having a T6 temper.